It is well known that snoring and obstructive sleep apnea are typically caused by a partial or complete obstruction of the pharyngeal airway during sleep. Mandibular advancement devices advance the mandible forward and consequently reduce the likelihood of the tongue and pharyngeal tissues from restricting the airway.
A number of mandibular advancement oral appliances have been proposed in the prior art. For example, U.S. Pat. No. 6,983,752, issued to Garabadian, discloses a mandibular advancement device that includes bite pads on maxillary and mandibular trays. The bite pads are located in a posterior portion of the device. The bite pads on the mandibular tray are located anterior to the bite pads of the maxillary tray. As such, when the user bites down, the mandible is extended outward due to the placement of the bite pads. That is, the anterior bite pads on the mandibular tray are held forward by the contact with the posterior bite pads on the maxillary tray. This device thus requires bite pads on both the mandibular and the maxillary trays in order to advance the mandible to the desired position.
U.S. Pat. No. 7,637,262 to Bailey discloses an oral appliance having features similar to those disclosed by Garabadian, and further includes the feature that the bite pads may form a guide plane for advancing the mandibular tray along the guide plane upon vertical closure between the trays.
Similarly, U.S. Pat. No. 6,604,527 to Palmisano discloses a mandibular advancement device that requires engaging members on both the mandibular and maxillary trays to advance the mandible. Palmisano's device includes lower flanges on a lower plate which have a trailing edge that engages with a leading edge of an upper flange that is disposed on an upper plate. The flanges are all located in a posterior portion of the device. The positioning of the flanges causes the mandible to be advanced when the device is used.
Because the Garabadian, Bailey and Palmisano devices require engaging members (e.g., bite pads, flanges, etc.) on both an upper and a lower tray, the devices can be cumbersome and awkward for a patient to wear, particularly for a full night's sleep and may cause dental/muscle/TMJ pain if the patient bruxes/clenches the teeth. Moreover, the fact that at least four engaging members are required in these devices increases the complexity of the device and increases the likelihood of failure of the device due to the failure of any individual engaging member. If the patient's mouth drops open during sleep, especially in the deeper stages of sleep (stages N3 and REM), the bite pads or guide members can disengage and allow the mandible and tongue to fall back into the oropharynx, obstructing the airway.
U.S. Pat. No. 7,451,767 to Keropian discloses an oral appliance that includes a “transpalatal bar” which extends across the posterior region of the appliance and acts as a tongue depressor to open the air passage. Posterior projections/extensions may be formed on the transpalatal bar, which hold the tongue down even further to further open the airway. However, Keropian's “transpalatal bar” is located on the underside of the appliance which is fitted to the palate and covers the upper teeth. Thus, the bar is located no lower (lingual side) than the occlusal surface of the posterior maxillary teeth. As such, the extent of tongue depression provided by the transpalatal bar is limited and can create problems if extended further down into the oropharynx. There is a problem with this design activating the gag reflex, which may not be well tolerated by many patients. This prior art appliance requires multiple follow up office visits to extend the “transpalatal bar” down the posterior aspect of the tongue to hold it forward. Regurgitation of stomach acid/digestive enzymes is also a problem while sleeping as this design does not allow the patient to swallow normally, preventing the tongue from creating a pharyngeal seal, resulting in a “reverse swallow” when in the mouth. This results in a negative esophageal pressure (partial vacuum) to develop in the esophagus and pharynx, causing the gastric contents to be “sucked up” from the stomach into the esophagus, pharynx, oral, nasal, and sinus cavities. This could be described as a form of “Iatrogenic” Gastric Esophageal Reflux Disorder (GERD), which has significant morbidity and even mortality as a long-term outcome.
Thus, there is a need in the field for a mandibular advancement oral appliance that can treat or alleviate symptoms caused by snoring and obstructive sleep apnea by advancing the mandible with a simpler device that requires fewer engagement members than required in the prior art. Furthermore, there is a need in the field for an oral appliance that can advance the mandible and retain the patient's tongue in a non-obstructive forward position when the tongue and pharyngeal muscles relax during the deepest stages of sleep, without significant side effects such as GERD.